A freethinking firm makes its mark exploring the intersections between public and private, indoors and out, function and form.

The al fresco living space of Anjo House, by Suppose Design Office, in Japan’s Aichi prefecture.CreditCreditTetsuya Miura

ON A MAY morning that was somewhere between rainy and sunny, in a Tokyo neighborhood that was somewhere between Shibuya and Shinjuku, I arrived at a nondescript brown-tiled building to visit Makoto Tanijiri and Ai Yoshida, the 44-year-old principals of Suppose Design Office, a Japanese architecture firm known for its raw, unfinished aesthetic — bookcases made from shipping pallets, houses with gaping holes instead of windows — that has been frequently praised and often copied in recent years. Suppose, which has more than 35 employees between this office and another in Hiroshima, and which is responsible for some of the most idiosyncratic contemporary homes and offices throughout Japan, moved into this partly below-ground space in late 2016.

In a departure from convention, they built a workspace entirely open to the public: If someone could bring her laptop to a coffee shop and call it her office, couldn’t an office do the reverse, inviting people in from the street for an obsessively crafted cup of cold brew? Suppose even branded its own bags of arabica beans for this exercise, lining them up beside a library of design books, which customers can browse while drinking espresso near high windows that look onto the sidewalk. In the back of the 2,058-square-foot room, beyond a steel coffee bar, a dozen architects meet in small groups or draft plans on computers in rows on long tables, performing their jobs in plain view of a largely disinterested audience. Sitting in the cafe can be an odd and exhilarating experience, like sneaking backstage in the tense moments before a play begins. But after a few sips, you ease into it, enjoying the quiet bustle; you become part of a human machine that toggles between labor and leisure.

Architecture, after all, dictates behavior: Public or private, indoor or outdoor, extravagant or humble, old or new, fake or real — these are a few of the obvious binaries by which we assess the spaces we inhabit. They are also the edges against which most architects hone their signature styles. But since their firm was founded 18 years ago, Tanijiri and Yoshida have instead devoted themselves to the liminal place where these elements break down; their designs (from a suburban house in Higashi with a dirt floor to a Tokyo cafe that transforms into a hostel) unite concepts that seem opposed. They aren’t interested in referencing the codes of Japan’s architecture establishment — nor in iterating upon their own past successes, as many distinguished firms do — but rather in envisioning new spaces that rest somewhere between the disquieting and the thrilling.

The house’s asphalt-shingled exterior has three open sides, bringing a garden and an ash tree into the interior.CreditTetsuya Miura

THIS ETHOS IS perhaps best captured in Tanijiri’s own apartment, designed in 2015. (As might be expected from a pair that specializes in indistinct boundaries, the two were once romantic partners as well, though this was never Yoshida’s residence.) On the fifth floor of a mid-1970s building in Hiroshima — now a bicycling haven on the southern shore of Japan, where they both grew up — Tanijiri wanted to find “completeness in incompletion.” Rather than build a home, he unbuilt one, dismantling nearly all the existing walls, exposing rusty pipes and cement foundations. He then subtly demarcated the 1,270-square-foot space, employing casement doors and windows, shelving and entryway arches — all in steel. The furniture is little more than a huge cushion covered in patchwork indigo denim atop matching steel floors and a few wooden dining chairs.

As with most contemporary Japanese architecture, simplicity does not necessarily mean ease or lack of complexity: Tanijiri’s home requires constant upkeep. Like a good Japanese knife, all of the steel demands incessant cleaning and polishing or it will rust before acquiring its desired blue-gray patina over the next few years. The metal’s transformation, though beautiful, is actually a form of controlled decay; the process speaks to Suppose’s obsession with permeable materials, such as concrete and unfinished wood, which require constant maintenance, and then, despite care, still diminish over time.

But perhaps the most compelling aspect of the disassembled apartment is the one that escaped destruction: Located near a window at the back corner of the living area is a traditional Japanese-style room that came with the place, with tatami-mat floors and shoji-screen walls. Without this flourish, the home might feel like the industrial lofts that have overtaken New York, London and other Western capitals. But by integrating the local vernacular, the project helps demonstrate why dozens of corporations have hired Suppose to bring their Western sensibilities east: In 2015, for the 40th anniversary of the French fashion brand Agnès B., Suppose skinned the company’s Ginza flagship store in pine plywood, which will wear over time to mirror the natural textures of the line’s custom fabrics; when Airbnb opened its Tokyo office in 2016, the architects created internal parks dappled with delicate Amazon olive trees.

The concrete exterior of a house near Hiroshima, perched on a hill above rail tracks, is stained a rusty hue that may redden over time.CreditTetsuya Miura